The present invention relates to a method for improving the directional characteristic of an echo sounder receiving base including a plurality of transducers arranged in a plane by means of multiplicative processing of output signals obtained from the signals received by the transducers from a submarine or underwater sound wave generator with a constant transmitting frequency and to apparatus for practicing the method.
In the echo sounding art, it is customary to utilize echo sounder receiving bases which comprise only a small number of transducers and thus do not take up much space. This arrangement, however, produces an unfavorable curve for the directional characteristic which has a broad main lobe and large side lobes. A broad main lobe, however, prevents an accurate determination of the direction of impinging echo signals whereas large side lobes may greatly falsify the determination of the direction.
German Offenlegungsschrift (Laid Open Patent Application) No. 2,347,732, published Apr. 4, 1974, which corresponds to U.S. Pat. No. 3,889,227 discloses a method of obtaining an improvement in the directional characteristic of an echo sounder receiving base by multiplicative processing of the signals received by the transducers.
This method, however, operates with a specially designed echo sounder receiving base, including pairs of transducers which must be arranged at given distances from one another. Such a receiving base is not suited to produce an improvement of the directional characteristic of a planar echo sounder receiving base including any desired number and arrangement of transducers.